This is an application requesting purchase of a PerSeptives Biosystems Voyager DE delayed extraction matrix assisted laser desorption/ionization-time of flight mass spectrometer (MALDI-TOF MS) for use in biochemical and structural research projects by twelve NIH- supported research groups. The MALDI-TOF MS will be used primarily for mapping of peptides and protein domains, quality control (synthesis of peptide and oligonucleotide derivatives, production of recombinant proteins, isotope enrichment of peptides and proteins), and assessment of chemical modifications of proteins. The Principal Investigator and the Major Users are all experienced researchers who use MS as an integral part of their research. There are no accessible mass spectrometer on campus, and each of us currently send samples for free- for-service facilities or off-campus collaborators for analysis. However, because of the expense and delay time, MS is used in the final stages of analysis rather than on a routine basis. All of us have experiments planned that would benefit enormously from having an instrument available for hands-on use at an around-the-clock basis, and we would expand the scope of research to exploit this resource. We anticipate that the requested MALDI-TOF MS would be used to analyze literally thousands of samples per year and would result in a significant increase in productivity. More importantly, this resource will allow the investigators to expand their research in new directions, and to begin new projects which could not have previously been undertaken.